26,830 research outputs found

    Proposal for a High Energy Nuclear Database

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    We propose to develop a high-energy heavy-ion experimental database and make it accessible to the scientific community through an on-line interface. This database will be searchable and cross-indexed with relevant publications, including published detector descriptions. Since this database will be a community resource, it requires the high-energy nuclear physics community's financial and manpower support. This database should eventually contain all published data from Bevalac, AGS and SPS to RHIC and LHC energies, proton-proton to nucleus-nucleus collisions as well as other relevant systems, and all measured observables. Such a database would have tremendous scientific payoff as it makes systematic studies easier and allows simpler benchmarking of theoretical models to a broad range of old and new experiments. Furthermore, there is a growing need for compilations of high-energy nuclear data for applications including stockpile stewardship, technology development for inertial confinement fusion and target and source development for upcoming facilities such as the Next Linear Collider. To enhance the utility of this database, we propose periodically performing evaluations of the data and summarizing the results in topical reviews.Comment: 8 pages, 3 figures. Proceedings of the 21st Winter Workshop on Nuclear Dynamics, Breckenridge, Colorado, February 5--12, 200

    Parton densities and structure functions at next-to-next-to-leading order and beyond

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    We summarize recent results on the evolution of unpolarized parton densities and deep-inelastic structure functions in massless perturbative QCD. Due to last year's extension of the integer-moment calculations of the three-loop splitting functions, the NNLO evolution of the parton distributions can now be performed reliably at momentum fractions x >= 10^-4, facilitating a considerably improved theoretical accuracy of their extraction from data on deep-inelastic scattering. The NNLO corrections are not dominated, at relevant values of x, by their leading small-x terms. At large x the splitting-function series converges very rapidly, hence, employing results on the three-loop coefficient functions, the structure functions can be analysed at N^3LO for x > 10^-2. The resulting values for alpha_s do not significantly change beyond NNLO, their renormalization scale dependence reaches about +-1% at N^3LO.Comment: 10 pages, LaTeX, 6 figures. Talk presented at the workshops `New Trends in HERA Physics 2001', Ringberg Castle (Germany), June 2001 and `DIS 2001', Bologna (Italy), April 2001. To appear, slightly shortened in the latter case, in the proceeding

    Suited for spacewalking: A teacher's guide with activities

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    This publication is an activity guide for teachers on spacesuits and spacewalking. It uses the intensive interest many children have in space exploration as a launching point for hands-on-opportunities. The guide begins with brief discussions of the space environment, the history of space walking, the Space Shuttle spacesuit, and working in space. These are followed by a series of activities that enable children to explore the space environment as well as the science and technology behind the functions of spacesuits. The activities are not rated for specific grade levels because they can be adapted for students of many ages. The guide concludes with a brief glossary as well as references and resources

    Labor Rights in the Generalized System of Preferences: A 20-Year Review

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    [Excerpt]In the fall of 1982, a small group of labor, religious, and human rights activists began charting a new course for human rights and workers\u27 rights in American trade policy. The principles of these labor rights advocates were straightforward: 1. No country should attract investment or gain an edge in international trade by violating workers\u27 rights; 2. No company operating in global trade should gain a competitive edge by violating workers\u27 rights; and, 3. Workers have a right to demand protection for labor rights in the international trade system, and to have laws to accomplish it. The coalition that took shape 20 years ago made a labor rights amendment to the Generalized System of Preferences (GSP), the chief policy vehicle in U.S. law to promote these principles. This article reviews 20 years\u27 experience with the GSP labor rights clause

    The Quark Form Factor at Higher Orders

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    We study the electromagnetic on-shell form factor of quarks in massless perturbative QCD. We derive the complete pole part in dimensional regularization at three loops, and extend the resummation of the form factor to the next-to-next-to-leading contributions. These results are employed to evaluate the infrared finite absolute ratio of the time-like and space-like form factors up to the fourth order in the strong coupling constant. Besides for the pole structure of higher-loop QCD amplitudes, our new contributions to the form factor are also relevant for the high-energy limit of massive gauge theories like QED. The highest-transcendentality component of our results confirms a result recently obtained in N=4 Super-Yang-Mills theory.Comment: 16 pages, 1 figure, Late

    Parton densities and structure functions beyond the next-to-leading order

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    We briefly discuss recent results on the evolution of unpolarized parton densities and structure functions in massless perturbative QCD. Present partial results on the next-to-next-to-leading order (NNLO) evolution kernels prove sufficient for reliable calculations at not too small values of the Bjorken variable, x > 10^-3. One order more can be taken into account at x >= 0.2. Inclusion of these terms considerably reduces the main theoretical uncertainties of determinations of alpha_s (to about 1% at the Z-mass) and the parton densities from structure functions.Comment: 6 pages LaTeX including 6 eps-figures. Talk presented at `Loops and Legs in Quantum Field Theory', Bastei (Germany) April 2000. To appear in the proceedings [Nucl. Phys. B (Proc. Suppl.)
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